Head Gasket Matching Problem.
Thread Starter
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Head Gasket Matching Problem.
Okay, the basics are I am installing after marker aluminum Vortec heads on a Gen1 400 block. I know I have to drill the steam holes, but I am seeing some matching problems between the gasket and the head and need to get a few things clear.
First, in the yellow squares, are a water port that doesn't match with the cutout in the head. Two per head, and one other that doesn't have a hole. I can enlarge the cutouts to match the openings in the head or will they be okay as is?
Also, I have shown a water port circled in red. That same red circle represents larger water ports UNDER the gasket, where a single tiny cutout exists. Should I open up those cutouts to match the water ports?
I have not checked these gaskets against the block yet but being that they are gaskets for a 400 they should match the block already.
Here are the pics, again, the yellow squares are the ports that don't match, and the red circles are where the ports are bigger than the cutouts.
First, in the yellow squares, are a water port that doesn't match with the cutout in the head. Two per head, and one other that doesn't have a hole. I can enlarge the cutouts to match the openings in the head or will they be okay as is?
Also, I have shown a water port circled in red. That same red circle represents larger water ports UNDER the gasket, where a single tiny cutout exists. Should I open up those cutouts to match the water ports?
I have not checked these gaskets against the block yet but being that they are gaskets for a 400 they should match the block already.
Here are the pics, again, the yellow squares are the ports that don't match, and the red circles are where the ports are bigger than the cutouts.
Burning Brakes
Joined: Feb 2000
Posts: 1,246
Likes: 1
The red area is normal, the gasket hole is smaller to "meter" coolant flow. Same as you would do by installing deck plugs and then drilling a hole )but it really is to reinfoce the deck but only a small hole is needed for proper flow). Do not open them up.
The other 2 small ones are so that you can use the same gasket on both banks (cheaper to produce)
The yellow square being off, well that's nothing out of the ordinary. Those gaskets are made to work with any available head, there's a bit of tolerance in the placing of the jackets and holes depending on chamber shape and port shape (they're simply cast in) as such the shape isn't even consistent, some are round, some are sort of triangular...it differs per head.
The other 2 small ones are so that you can use the same gasket on both banks (cheaper to produce)
The yellow square being off, well that's nothing out of the ordinary. Those gaskets are made to work with any available head, there's a bit of tolerance in the placing of the jackets and holes depending on chamber shape and port shape (they're simply cast in) as such the shape isn't even consistent, some are round, some are sort of triangular...it differs per head.
Last edited by V-Twin; Jun 18, 2008 at 05:53 PM.
Thread Starter
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
The red area is normal, the gasket hole is smaller to "meter" coolant flow. Same as you would do by installing deck plugs and then drilling a hole )but it really is to reinfoce the deck but only a small hole is needed for proper flow). Do not open them up.
The other 2 small ones are so that you can use the same gasket on both banks (cheaper to produce)
The yellow square being off, well that's nothing out of the ordinary. Those gaskets are made to work with any available head, there's a bit of tolerance in the placing of the jackets and holes depending on chamber shape and port shape (they're simply cast in) as such the shape isn't even consistent, some are round, some are sort of triangular...it differs per head.
The other 2 small ones are so that you can use the same gasket on both banks (cheaper to produce)
The yellow square being off, well that's nothing out of the ordinary. Those gaskets are made to work with any available head, there's a bit of tolerance in the placing of the jackets and holes depending on chamber shape and port shape (they're simply cast in) as such the shape isn't even consistent, some are round, some are sort of triangular...it differs per head.
Thank you, that was very good information.
I have seen gaskets not match before but this was more extreme than I had experienced and was wondering if I had a mismatch between the gaskets, or even the heads and the block. I've never built a 400 besides this one, and these certainly aren't stock 400 heads.
So basically I shouldn't have to do anything but mark and drill the steam holes.
Thread Starter
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
The paper I read that outlined it showed that the steam holes closest to the bolt bosses needed to be drilled at a 45 degree angle away from them. As V-twin said, the other side straight down. I think so long as the bit doesn't get into the bolt boss it doesn't matter.
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Thread Starter
Team Owner
Joined: Aug 2006
Posts: 24,125
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From: Columbia Missouri
No this is mine. I built this 405 a few years ago, but stalled on the fuel injection setup. In the last few weeks I re-planned the build for more power, and changed to a carb setup with an option to go FI later.
It's a very different setup than what I am used to...lots of new things for me.
Thread Starter
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Well I must say I'm a bit stumped. Started drilling the steam holes this morning. The exhaust side holes went smooth and perfect. However, the intake side, just off from the head bolt boss, is confusing me. I know these are after market Vortec castings but I have buried the bit a full inch and it hasn't broken into the cooling jacket yet. I tried the 30 degree angle, away from the bolt boss.
Any ideas? I straight in, and straight down, at the angle, but nothing. I don't want to punch into the center exhaust port passages.
Any ideas? I straight in, and straight down, at the angle, but nothing. I don't want to punch into the center exhaust port passages.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
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From: Unreconstructed, South Carolina
Maybe this'll assist:
http://www.gregsengine.com/350to400.htm
I know the article's captions read 10* but it sure looks like head's indexed about 30*
http://www.gregsengine.com/350to400.htm
I know the article's captions read 10* but it sure looks like head's indexed about 30*
Thread Starter
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Maybe this'll assist:
http://www.gregsengine.com/350to400.htm
I know the article's captions read 10* but it sure looks like head's indexed about 30*
http://www.gregsengine.com/350to400.htm
I know the article's captions read 10* but it sure looks like head's indexed about 30*
Yeah I have the location and the angles right on I think, but the depth of the second set is scaring me. Like I said I am already at almost a full 1" depth, which is considerably deeper than what I've read before. However, these are after market aluminum casting so there may be more material to drill through.
I checked with a local machine shop, they have never drilled steam holes in aluminum after market heads, and want $50 per head just in case something goes wrong so they can cover their own ***.
Thread Starter
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
